This invention relates to voltage level shifting, and more particularly to controlled voltage level shifting that is operable over various operating and environmental conditions.
Modern electronic products and devices are complex systems that include many sub-systems. For example, a computer system can include disk drives, random access memory, and graphics hardware, among other things. To facilitate integration and compatibility of different electronic components, industry standards organizations typically adopt operating and manufacturing standards for electronic components. Even with these standards, however, it can still be a challenge to satisfy the various requirements of different components.
Operating standards for an electronic component often specify voltage-related requirements. One such requirement is operating voltage. Components may require voltage source levels of +1.2 volts (V), +3.3 V, or +5.0 V, for example. Another voltage-related operating requirement may be voltage swing. A single power supply may not be able to accommodate the voltage requirements of all of the various sub-systems. More importantly, different sub-systems having different voltage-related requirements may need to communicate signals between each other. Therefore, a system may need voltage adjustment circuitry to integrate different components in an electronic system and to accommodate their voltage-related requirements.
One type of voltage adjustment circuit is a voltage level shifter, which receives a voltage waveform and, preferably, shifts the waveform by a desired voltage level without altering the shape or content of the waveform. High performance voltage level shifters are generally implemented using analog implementations, which can accommodate high frequency waveforms and which do not distort a waveform by sampling and quantization, as is common with digital implementations. However, an analog implementation may suffer from sensitivities to undesirable operating or environmental conditions, such as temperature variations and/or power supply noise, for example. Thus, it would be desirable to provide a high performance voltage level shifter that operates over a variety of operating and/or environmental conditions.